In manufacturing semiconductor devices, a liquid processing such as, for example, a cleaning processing or a wet etching processing is performed on a substrate such as a semiconductor wafer. In order to perform such a liquid processing, a liquid processing system provided with a plurality of liquid processing modules (liquid processing units) is used. The liquid processing system is provided with a processing liquid storing tank, a circulation line that goes out of the processing liquid storing tank and goes back to the processing liquid storing tank, and a pump configured to form a flow of a pressurized processing liquid in the circulation line. A plurality of branch lines branches in parallel from the circulation line, and the processing liquid is supplied to each of the liquid processing modules from the branch lines. A flowmeter and a flow control valve are interposed in each of the branch lines. Based on a detection value of the flowmeter, a feedback control of the flow control valve is performed such that a flow rate of the processing liquid supplied to a substrate by the liquid processing module becomes a desired value (see, for example, Japanese Patent No. 3841945).
When a valve body of the flow control valve is moved frequently in the feedback control, particles may be generated inside the flow control valve. The generated particles are supplied to a substrate along with the processing liquid passing through the branch lines. Here, when the particles are generated at a problematic level, it is necessary to provide a filter to remove the particles. However, provision of a filter causes a problem in that a regular maintenance of the filter is required.